Factory Chevrolet parts manuals are a good place to start. Try to pick up some from (and I'm speculating here) 1970-75. Those should have most of the part numbers you need inside. You can use the parts manual in conjunction with the assembly manual to figure out most of what you'll need. Keep in mind none (any?) of the numbers will be any good at the local Chevy store, but you can use them to figure out what you'll need.

As far as tracking down old parts catalogs, others here are probably a better resource than me (I must have a half dozen full dog-eared sets and I'm not parting with 'em <g&gt.

Wayne Scraba